This invention relates generally to injection molding and more particularly to a heated nozzle upon which a thermocouple element can be removably mounted in a predetermined position and be securely self-retained in place.
It is well known to use a thermocouple element to continuously measure the temperature in a heated injection molding nozzle. In order to monitor the operating temperature near the gate, it is important that the thermocouple in the front portion of the thermocouple element be positioned near the front end of the nozzle. It is also very critical that the thermocouple in each nozzle be very accurately positioned. Thus the thermocouple element must be mounted so that it is securely retained in place, particularly during installation of the nozzle in the mold. An example of the thermocouple being positioned near the front end of the nozzle is shown in the applicants' U.S. Pat. No. 4,768,283 which issued Sep. 6, 1988 where the thermocouple element extends into the insulative air space through a thermocouple duct through the rear collar portion of the nozzle. While the thermocouple element is bent into a groove in the rear end of the nozzle, there is no provision for retaining the thermocouple in place during installation.
More recently, the applicants' Canadian patent application Ser. No. 2,078,890 filed Sep. 22, 1992 entitled "Injection Molding Nozzle with Thermocouple Receiving Torpedo" shows the thermocouple retained in position by a wire wrapped around the nozzle to hold the thermocouple element in place against it. In the applicants' Canadian patent application Ser. No. 2,091,409 filed Mar. 10, 1993 entitled "Injection Molding Torpedo with Thermocouple Bore" the thermocouple is held in place by the thermocouple element extending radially outward into contact against a tapered portion of the well in the mold. However, this does not ensure that the thermocouple is retained in place during installation of the nozzle in the mold.